docs: update Prometheus integration steps and add federation setup instructions

[muhammetssen]

No description provided.

[Copilot]

Pull Request Overview

This PR enhances the Prometheus integration documentation by restructuring the setup instructions and adding comprehensive federation configuration guidance. It transforms a basic scraping guide into a more flexible integration approach that supports both direct Grafana connections and local Prometheus federation.

• Reorganized Step 4 to include both Grafana dashboard setup and Prometheus federation options
• Added detailed federation configuration with YAML examples and filtering options
• Improved section structure with clear use cases for when to choose federation over direct connection

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